Light emitting device and method of manufacturing same

ABSTRACT

A light emitting device includes: a rectangular substrate, a light emitting element, a reflective member disposed at one or more lateral sides of the light emitting element while being away from therefrom, a light guide member, and a light transmissive member on the light guide member. The reflective member includes one or more first reflective members opposing lateral faces of the light emitting element, and a second reflective member outside the first reflective member. The first reflective members have inner lateral faces opposing each other each having an oblique or curved portion slanted so that a distance therebetween increases towards the light transmissive member from a side close to the substrate. The second reflective member covers outer lateral faces of the light transmissive member and the first reflective members, and an upper face of the second reflective member is flush with an upper face of the light transmissive member.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.15/977,580, filed May 11, 2018, which claims priority to Japanese PatentApplication No. 2017-096014 filed on May 12, 2017, and Japanese PatentApplication No. 2018-033162 filed on Feb. 27, 2018, the disclosures ofwhich are hereby incorporated by reference in their entirety.

BACKGROUND

The present disclosure relates to a light emitting device and a methodof manufacturing the light emitting device.

For a light emitting device, for example, Japanese Unexamined PatentApplication Publication Nos. 2013-219397 and 2016-219743 each disclose astructure which includes a cover member disposed in the surrounding of alight emitting element.

SUMMARY

With respect to the light emitting devices disclosed in the patentpublications mentioned above, however, an increase in the lightextraction efficiency is desired.

Accordingly, one object of certain embodiments of the present disclosureis to provide a light emitting device having improved light extractionefficiency and a method of manufacturing such light emitting device.

The light emitting device related to certain embodiment of the presentdisclosure includes: a substrate in a shape of rectangular; a lightemitting element mounted on the substrate; a reflective member disposedat one or more lateral sides of the light emitting element while beingaway from therefrom; a light guide member filling in the reflectivemember so as to cover the light emitting element positioned in/betweenthe reflective member; and a light transmissive member disposed on thelight guide member. The reflective member includes at least one firstreflective member opposite lateral faces of the light emitting element,and a second reflective member positioned outside the first reflectivemember and surrounds the light emitting element. The first reflectivemembers have inner faces opposite each other, the inner faces eachhaving an oblique or curved portion that are slanted so that a distancetherebetween increases towards the light transmissive member from a sideclose to the substrate. The second reflective member covers the lateralfaces of the light transmissive member and outer lateral faces of thefirst reflective members, and an upper face of the second reflectivemember is flush with an upper face of the light transmissive member.

The method of manufacturing a light emitting device related to othercertain embodiment of the present disclosure includes: arranging aplurality of light emitting elements on a substrate; disposing firstreflective members so as to positioned between or surrounding the lightemitting elements while being away from the light emitting elements;disposing a light guide member covering the light emitting elements andin contact with the first reflective members; disposing a lighttransmissive member on the light guide member and the first lightreflective members; forming first grooves by partially removing thelight transmissive member and the first reflective members; disposing asecond reflective member in the first grooves so as to be in contactwith the light transmissive member and the first reflective members; andseparating into individual pieces by cutting the second reflectivemember.

According to the light emitting device related to certain embodiment ofthe present disclosure, the light extraction efficiency can be increasedbecause the space surrounded by the reflective members and the lighttransmissive member is filled with the light guide member. In addition,the oblique or curved portion of the inner faces of the first reflectivemembers being away from each other allows more light to propagate over awide expanse of space.

The method of manufacturing a light emitting device related to theembodiment of the present disclosure can manufacture, in a simplifiedmanner, a light emitting device in which the first reflective membershave the oblique or curved portion in the inner faces, the secondreflective member forms the outer walls of the light emitting device,and the light guide member fills the space that surrounds the lightemitting element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a light emitting device according to afirst embodiment viewed from the emission face side.

FIG. 2 is a perspective view of a light emitting device according to thefirst embodiment viewed from the electrode side.

FIG. 3A is a perspective sectional view of a light emitting deviceaccording to the first embodiment, the section being in parallel to thelong sides and perpendicular to the emission face.

FIG. 3B is a sectional view of a light emitting device according to thefirst embodiment, the section being in parallel to the long sides andthe emission face.

FIG. 3C is a sectional view of a light emitting device according to thefirst embodiment, the section being in parallel to the short sides andperpendicular to the emission face.

FIG. 4 is a flowchart showing one example of a method of manufacturingthe light emitting device related to the first embodiment of the presentdisclosure.

FIG. 5A is a plan view of a substrate in which some components areomitted for ease of explanation of the step of arranging light emittingelements shown in the flowchart in FIG. 4.

FIG. 5B is a sectional view for explaining the step of disposing firstreflective members shown in the flowchart in FIG. 4.

FIG. 5C is a sectional view for explaining the step of disposing a lightguide member shown in the flowchart in FIG. 4

FIG. 5D is a sectional view for explaining the removal step shown in theflowchart in FIG. 4.

FIG. 5E is a sectional view for explaining the step of disposing lighttransmissive members shown in the flowchart in FIG. 4.

FIG. 5F is a sectional view for explaining the step of forming firstgrooves and the step of forming second grooves shown in the flowchart inFIG. 4.

FIG. 5G is a sectional view for explaining the step of disposing asecond reflective member shown in the flowchart in FIG. 4.

FIG. 5H is a sectional view explaining the step of separating intoindividual pieces shown in the flowchart in FIG. 4.

FIG. 6A is a plan view for explaining the step of forming first groovesand the step of forming second grooves shown in the flowchart in FIG. 4.

FIG. 6B is a plan view for explaining the step of disposing a secondreflective member shown in the flowchart in FIG. 4.

FIG. 6C is a plan view for explaining the step of separating intoindividual pieces shown in the flowchart in FIG. 4.

FIG. 7 is a schematic sectional view of a light emitting deviceaccording to a second embodiment.

FIG. 8 is a sectional view for explaining a manufacturing process for alight emitting device according to the second embodiment.

FIG. 9 is a schematic sectional view of a light emitting deviceaccording to a third embodiment.

FIG. 10 is a schematic sectional view of a light emitting deviceaccording to a fourth embodiment.

FIG. 11 is a schematic sectional view of a light emitting deviceaccording to a fifth embodiment.

FIG. 12 is a schematic sectional view of a light emitting deviceaccording to a sixth embodiment.

FIG. 13A is a partial sectional view of a first reflective member in alight emitting device which is a variation of the embodiments of thepresent invention.

FIG. 13B is a partial sectional view of a first reflective member in alight emitting device which is another variation of the embodiments ofthe present disclosure.

DESCRIPTION

The light emitting device and the method of manufacturing the samerelated to certain embodiments will be explained below. The drawingsreferenced in the explanations given below are those that schematicallyshow the embodiments, and thus the relative sizes, spacing, positionalrelationship, and the like of the members might be exaggerated, or themembers might be partially omitted. In the explanations below, moreover,the same designations and reference numerals denote the same members orthose of similar quality as a general rule, for which detailedexplanations will be omitted when appropriate. Furthermore, FIG. 5A toFIG. 5H, FIG. 6A to FIG. 6C, and FIG. 8 only show a part of a wholestructure. In each drawing, the primary emission direction Br of thelight released from the light emitting device 10 is indicated with anarrow. In the explanations below, the emission direction Br of the lightreleased from the light emitting device 10 is explained as upward andthe reverse direction as downwards.

First Embodiment Light Emitting Device

As shown in FIG. 1 and FIG. 3A to FIG. 3C, the light emitting device 10includes a rectangular substrate 22, a light emitting element 16 mountedon the substrate 22, a light guide member 24 covering the light emittingelement 16, a light transmissive member 25 disposed on the light guidemember 24, a reflective member 17 disposed in the periphery of the lighttransmissive member 25 and the light guide member 24 so as to surroundthe light emitting element 16, electrodes of the light emitting element15, and wiring members 14. The light emitting device 10 emits light viathe light transmissive member 25 which is the emission face 12. In theexample shown in the drawings, the light transmissive member 25 includesa phosphor layer 26 and a light transmissive layer 28 stacked thereon.In the present disclosure, the phosphor layer 26 is not necessarilyrequired. In the explanations below, the light transmissive member whichincludes a phosphor layer 26 will be explained as an example. Moreover,the reflective member 17 includes first reflective members 18 disposedopposite the lateral faces of the light emitting element 16, and asecond reflective member 20 which is positioned on the outside of thefirst reflective members 18 and disposed to surround the light emittingelement 16.

Each constituent element will be successively explained below.

As shown in FIG. 3A to FIG. 3C, the light emitting element 16 includes alight transmissive substrate, semiconductor layers, and electrodes 15.The light emitting element 16 preferably has a rectangular shape whenviewed from top, particularly preferable to have a rectangular shapehaving long sides and short sides. The light emitting element 16 mayhave another shape and, for example, a hexagonal shape can increase theemission efficiency. The light emitting element 16 preferably haspositive and negative (p and n) electrodes on the same face. Moreover,the number of the light emitting elements 16 mounted in a light emittingdevice 10 may be one or more. In the case of including a plurality oflight emitting elements 16, they can be connected in series or parallel.

A light transmissive substrate may simply be one usually used inmanufacturing a semiconductor light emitting element; specifically, asapphire substrate is used. The semiconductor layers are a stack ofsemiconductor layers which include at least an n-type semiconductorlayer and a p-type semiconductor layer, and an active layer interposedtherebetween. A material of the semiconductor layers preferably employsa nitride semiconductor capable of emitting short wavelength light thatcan efficiently excite wavelength conversion substances. Nitridesemiconductors are primarily represented by the general formula,In_(x)Al_(y)Ga_(1-x-y)N (0≤x, 0≤y, x+y≤1). Furthermore, the electrodes15 are formed on one face. The electrodes 15 need to be mountable metalmaterials, but the type of metal is not particularly limited as long asthey are conductive members capable of achieving an electricalconnection. The electrodes 15 are bonded to the substrate 22 (describedlater) via a bonding member.

The bonding member can simply be interposed between the electrodes 15 ofthe light emitting element 16 and the wiring members 14 of the substrate22. For example, the bonding member can be disposed in the regions ofthe wiring members 14 on the substrate 22 where the light emittingelement 16 is to be mounted, or on the electrodes 15 of the lightemitting element 16, or both. The bonding member can be in the form of aconductive liquid or paste. The application method of the bonding membercan be suitably selected from among potting, printing, transfer process,or the like, depending on the viscosity or the like.

The substrate 22 is constructed with at least wiring members 14 and abase that supports the wiring members 14.

The wiring members 14 are formed at least on the upper face (i.e., frontface) of the base, and may also be formed inside of and/or on thelateral faces and/or on the lower face (i.e., back face) of the base.The wiring members 14 can be formed, for example, with copper or acopper alloy. In the case of employing a rigid substrate for the base, aresin, fiber reinforced resin, ceramic, glass, metal, paper, or the likecan be used. It is particularly preferable to employ a material of thebase that has a coefficient of linear expansion closer to that of thelight emitting element.

The light guide member 24 is disposed to fill the space between thelight emitting element 16 and the reflective member 17 and encapsulatesthe light emitting element 16 mounted on the substrate 22. For the lightguide member 24, a material having good light transmission propertiesrelative to the wavelength of the light emitted by the light emittingelement 16 as well as having good weather resistance, light resistance,and heat resistance may be used to serve as an encapsulant. By disposingthe light guide member 24 on the lateral faces of the light emittingelement 16, the light released from the lateral faces of the lightemitting element 16 can be more efficiently guided to the lighttransmissive member 25. This can alleviate the loss of light, therebyincreasing the light extraction efficiency of the light emitting device10.

Examples of the materials employed for the light guide member 24 includethermoplastic resins and thermosetting resins. For thermoplastic resins,for example, polyphthalamide, liquid crystal polymers, polybutyleneterephthalate (PBT), unsaturated polyester, or the like can be used. Forthermosetting resins, for example, epoxy resins, modified epoxy resins,silicone resins, modified silicone resins, or the like can be used.

The reflective member 17 constructs the lateral walls of the lightemitting device, and reflects the light from the light emitting element16 to be extracted from the emission face 12. The reflective member 17includes first reflective members 18 and a second reflective member 20.The reflective member 17 can increase the light extraction efficiency byutilizing the first reflective members 18 and the second reflectivemember 20.

The reflective member 17 preferably has a reflectance of 70% or higher,more preferably 80% or higher, even more preferably 90% or higher, forthe peak emission wavelength of the light emitting element, from thestandpoint of light extraction efficiency in the forward direction.Furthermore, the reflective member 17 is preferably white. Accordingly,the reflective member 17 is preferably constructed with a base materialcontaining a white pigment.

A resin can be used as the base material of the reflective member 17,for example, a silicone resin, epoxy resin, phenol resin, polycarbonateresin, acrylic resin, or modified resin of these. Among these examples,silicone resins and modified silicone resins are preferable because theyare highly heat resistant and highly light resistant. Specific examplesof silicone resins include dimethyl silicone resins, phenylmethylsilicone resins, and diphenyl silicone resins. The base material of thereflective member may contain various fillers in the resins mentionedabove. Examples of fillers include silicon oxide, aluminum oxide,zirconium oxide, zinc oxide, and the like. One or a combination of twoor more of these fillers can be used. Particularly, silicon oxide ispreferable due to its small coefficient of thermal expansion.Furthermore, using nanoparticles for the filler can increase scattering,including Rayleigh scattering, of blue light emitted by the lightemitting element, and thus can also reduce the amount of the wavelengthconversion substance used. Nanoparticles are particles whose diametersare in a range of from 1 nm to 100 nm. The “particle diameter” herein isdefined, for example, by D₅₀.

For the white pigment, one or a combination of two or more of titaniumoxide, zinc oxide, magnesium oxide, magnesium carbonate, magnesiumhydroxide, calcium carbonate, calcium hydroxide, calcium silicate,magnesium silicate, barium titanate, barium sulfide, aluminum hydroxide,aluminum oxide, and zirconium oxide can be used. Particle shapes of thewhite pigment are not particularly limited, and may be a irregular ornon-uniform shape or a crushed shape. A spherical shape is preferablefrom the fluidity standpoint. The particle diameter of the whitepigment, for example, is from about 0.1 μm to about 0.5 μm. In order toenhance the light reflection properties and the effectiveness ofcoverage, the smaller the particle diameter, the more preferable it is.The white pigment content of the reflective member can be suitablyselected, and from the standpoint of light reflection properties orviscosity in a liquid state, for example, it is preferably in a range offrom 10 wt % to 80 wt %, more preferably from 20 wt % to 70 wt %, evenmore preferably from 30 wt % to 60 wt %. The term “wt %,” which isweight percent, represents the weight ratio of the applicable materialto the total weight of the first reflective members 18 or the secondreflective member 20.

In the case of employing a light emitting element 16 having long sidesand short sides in a top view, the first reflective members 18 aredisposed opposite the short sides of the light emitting element 16. Thefirst reflective members 18 have opposing oblique or curved portions inthe inner lateral faces 19 that are slanted so that the distancetherebetween becomes wider towards the light transmissive member 25 fromthe substrate 22 side. In other words, each of the pair of first lighttransmissive members 18 has an oblique or curved portion in the innerface 19 that is slanted so that the distance between the two opposinginner faces gradually increases towards the emission direction Br fromthe substrate 22 side. The outer lateral faces of the first reflectivemembers 18 are disposed in the state of being in contact with the innerlateral faces of the second reflective member 20. The upper ends of thefirst reflective members 18 are disposed in the state of being incontact with the lower face of the phosphor layer 26. Furthermore, thefirst reflective members 18 are in contact with the lateral faces of thesubstrate 22 corresponding to the short sides, and the lower faces ofthe first reflective members 18 are flush with the lower face of thesubstrate 22. In the region where the second reflective member 20 isdisposed, part of the first reflective members 18 exist under the lowerend of the second reflective member 20 so that the lower end of thesecond reflective member 20 is positioned higher than the lower ends ofthe first reflective members 18. For the first reflective members 18,the same light reflecting material as that of the second reflectivemember 20 described below is used as an example.

The second reflective member 20 is disposed to surround the firstreflective members 18 and the light emitting element 16. The secondreflective member 20 forms the lateral walls of the light emittingdevice 10. The second reflective member 20 is disposed such that itsupper end is flush with the upper face of the light transmissive member25 while covering the lateral faces of the light transmissive member 25.Furthermore, as shown in FIG. 3C, the second reflective member 20 isdisposed so as to be in contact with the upper face edges of thesubstrate 22 along the long sides. A thickness of the second reflectivemember 20 is not specifically limited, but in FIG. 3A and the like, thethickness of the second reflective member 20 is set to one half of orsmaller than that of a first reflective member 18. The second reflectivemember 20 is preferably as thick as or thinner than the thickness of afirst reflective member 18. Forming the second reflective member 20thinly allows the emission face 12 to secure a larger area, therebypropagating the extracted light over a wide expanse of space.

The second reflective member 20 is produced by filling the groovescreated in the first reflective members 18 formed in accordance with thestep in the manufacturing method discussed later. The material of thesecond reflective member 20 whose thickness is set to be smaller thanthat of the first reflective members 18 may be of the same material asor different from that of the first reflective members 18. Here, bothmembers are being explained as employing the same material as oneexample, and the reflective member discussed earlier, for example, ispreferably used.

By way of this construction, the first reflective members 18 and thesecond reflective member 20 are less likely to absorb the light releasedfrom the light emitting element 16 and the phosphor. Moreover, the firstreflective members 18 and the second reflective member 20 play a role ofreflecting the light from the light emitting element 16 and the phosphorto guide the light to the emission face 12. Setting a small thicknessfor the second reflective member 20 allows the emission face 12 at theupper face of the light emitting device 10 to secure as large an area aspossible, thereby improving the light extraction efficiency.

The phosphor layer 26 is disposed on the first reflective members 18 andthe light guide member 24. The phosphor layer 26 converts the wavelengthof the light from the light emitting element 16. For example, the lightemitting element 16 emits blue light, and the wavelength conversionsubstance, which is a phosphor, in the phosphor layer 26 converts aportion of the blue light into, for example, yellow light. This allowsthe light emitting device 10 to emit the light resulting from mixing thecolors, e.g., white light. The phosphor layer 26 may contain severaltypes of wavelength conversion substances, and contain a filler similarto that contained in the reflective member described earlier instead of,or in addition to, a wavelength conversion substance.

The phosphor layer 26 can contain a wavelength conversion substance(e.g., phosphor) known in the art. Examples of wavelength conversionsubstances include cerium-activated yttrium aluminum garnet (YAG)-basedphosphors that emit green to yellow light, cerium-activated lutetiumaluminum garnet (LAG)-based phosphors that emit green light, europiumand/or chromium-activated nitride-containing calcium aluminosilicate(CaO-Al₂O₃-SiO₂)-based phosphors that emit green to red light,europium-activated silicate ((Sr,Ba)₂SiO₄)-based phosphors that emitblue to red light, β-SiAlON phosphors that emit green light,nitride-based phosphors, such as CASN-based phosphors expressed asCaAlSiN₃:Eu or SCASN-based phosphors expressed as (Sr,Ca)AlSiN₃:Eu, thatemit red light, K₂SiF₆:Mn (KSF)-based phosphors that emit red light,sulfide-based phosphors that emit red light, and the like.

The light transmissive layer 28 transmits the light from the phosphorlayer 26, the light from the light emitting element 16, and the lightfrom the reflective member 17 therethrough to be extracted. The upperface of the light transmissive layer 28 serves as the emission face 12.The light transmissive layer 28 is in contact with the phosphor layer 26and its lateral faces in contact with the second reflective member 20.The upper face of the light transmissive layer 28 and the upper face ofthe second reflective member 20 are formed to be flush with each other.The light transmissive layer 28 is preferably formed using a materialwhich has light transmitting properties, as well as having good weatherresistance, light resistance, and heat resistance to serve as anencapsulant.

The “light transmitting properties” here refers to a transmittance ofpreferably 60% or higher, more preferably 70% or higher, even morepreferably 80% or higher for the peak emission wavelength of the lightemitting element. Examples of the base material used for the lighttransmissive layer 28 include silicone resins, epoxy resins, phenolresins, polycarbonate resins, acrylic resins, or their modified resins.The base material of the light transmissive layer 28 may be glass. Amongsuch examples, silicone resins and modified silicone resins arepreferable for the base material of the light transmissive layer 28 dueto its highly heat resistant and light resistant. Specific examples ofsilicone resins include dimethyl silicone resins, phenylmethyl siliconeresins, and diphenyl silicone resins. The light transmissive member 25can be constructed with one of these base materials, or by stacking twoor more of these base materials. The base material of the lighttransmissive layer 28, which is the foregoing resins or glass, maycontain a filler similar to that contained in the base materials of thefirst reflective members 18 and the second reflective member 20described earlier.

The light emitting device 10 is constructed as above, and once light isemitted from the light emitting element 16, the light transmits throughthe light guide member 24 and then through the light transmissive member25 (i.e., the phosphor layer 26 and the light transmissive layer 28),and is extracted from the emission face 12. The oblique or curvedportions in the inner faces 19 of the first reflective members 18 allowa portion of the light from the light emitting element 16 to be morereadily extracted from the emission face 12. The second reflectivemember 20 which covers the lateral faces of the phosphor layer 26 andthe light transmissive layer 28 reflects light to be extracted from theemission face 12.

The first reflective members 18 each have a required thickness (e.g.,equal to or thicker than the substrate 22) and form a supporter for thelight emitting device 10 together with the substrate 22, therebymaintaining the strength of the light emitting device as a whole.Furthermore, disposing the phosphor layer 26 and the light transmissivelayer 28 above the upper ends of the first light reflective members 18can secure a wider area for the emission face 12 at the upper face ofthe light emitting device 10. Forming the oblique or curved portions inthe inner lateral faces 19 at the upper parts of the first reflectivemembers 18 facilitates the extraction of the light from the lightemitting element 16 through the emission face 12. Accordingly, the lightemitting device 10 has an improved light extraction efficiency andattenuated color non-uniformity.

Method of Manufacturing Light Emitting Device

Subsequently, a method of manufacturing the light emitting devicerelated to the first embodiment will be explained below.

As shown in FIG. 4, the method of manufacturing the light emittingdevice includes: arranging light emitting elements 16 (S101); disposingfirst reflective members 18 (S102); disposing a light guide member 24(S103); disposing a light transmissive member 25 (S105); forming firstgrooves 32 (S106); disposing a second reflective member 20 (S108); andseparating into individual pieces (S109). The method of manufacturingthe light emitting device may include a removal step (S104) followingthe step of disposing a light guide member 24 (S103), and may furtherinclude a step of forming second grooves 34 (S107) following the step offorming the first grooves 32 (S106). Each step will be explained below.

First, as shown in FIG. 4 and FIG. 5A, in the step of arranging lightemitting elements 16 S101, a plurality of light emitting elements 16 arearranged on the substrate 22 on which wiring members 14 have alreadybeen formed. It is preferable to arrange the light emitting elements 16via bonding members by flip chip mounting. The light emitting elements16 are arranged in rows and columns at predetermined intervals. Thelight emitting elements 16 are arranged using larger intervals for thearrangement in columns than the intervals for the arrangement in rows.Furthermore, the substrate 22 has through holes 22 a along the columns.The through holes 22 a are formed along the rows, more specifically,formed continuously along the positions opposite the short sides of thelight emitting elements 16, but not formed along the peripheral edges ofthe substrate 22. The operations are performed in the state where anadhesive sheet 30 is attached to the back face of the substrate 22.

In the step of disposing first reflective members 18 (S102), in thelight emitting elements 16 arranged in rows and columns on the substrate22, first reflective members 18 are disposed between the light emittingelements 16 along the columns. In other words, the first reflectivemembers 18 are disposed in the through holes 22 a formed along thecolumns in FIG. 5A. In detail, as shown in FIG. 5B, the first reflectivemembers 18 are disposed close to the both ends of the light emittingelements 16 to oppose the short sides thereof that are mounted on thesubstrate 22.

The first reflective members 18 provided with a preadjusted viscosityare disposed away from the light emitting elements 16 so as to maintainthe heights equal to or higher than the upper face of the substrate 22while penetrating the through holes 22 a. The through holes 22 a arecreated in the substrate 22 beforehand along the regions where the firstreflective members 18 are to be disposed, and an adhesive sheet 30 isapplied to the lower face side of the substrate 22 so as to close theopenings of the through holes 22 a. Thus, the lower faces of the firstreflective members 18 are formed to be flush with the lower face of thesubstrate 22. Furthermore, at the upper portions of the first reflectivemembers 18, oblique or curved portions are formed due to surface tensionand viscosity. The first reflective members 18 are disposed to be higherthan the upper ends of the light emitting elements 16. Alternatively, aguide may be placed on the substrate when disposing the first reflectivemembers 18 to achieve predetermined shapes and heights, thereafter theguide may be removed once the first reflective members 18 are cured. Thefirst reflective members 18 can be formed by transfer molding, injectionmolding, compression molding, potting, or the like.

Subsequently, as shown in FIG. 4 and FIG. 5C, in the step of disposing alight guide member (S103), the spaces between the first reflectivemembers 18 and the light emitting elements 16, and the spaces betweenthe light emitting elements 16, are filled with the light guide member24. Here, the light guide member 24 fills the spaces and to a height soas to bury the first reflective members 18 and the light emittingelements 16, followed by being cured. To cure the light guide member 24,it is preferably heated in the case of a thermosetting resin, orsubjected to ultraviolet light irradiation in the case of a UV curableresin, by intention. Examples of filling methods include transfermolding, injection molding, potting, and the like.

As shown in FIG. 4 and FIG. 5D, in the removal step S104, the lightguide member 24 and the first reflective members 18 are partiallyremoved to be flat and to maintain a height to allow the light guidemember 24 to present on the light emitting elements 16. The light guidemember 24 and the first reflective members 18 may be removed by using agrindstone, disk-shaped rotary blade, plane, or the like.

Subsequently, as shown in FIG. 4 and FIG. 5E, in the step of disposing alight transmissive member S105, the light transmissive member 25including the phosphor layer 26 and the light transmissive layer 28 isdisposed on the upper surfaces of the light guide members 24 and thefirst reflective members 18 via light transmissive joining material. Thephosphor layer 25 is formed using a sheet member containing at least onephosphor in advance. The light transmissive layer 28 is formed using asheet member. The sheet member serving as the phosphor layer 26 containsat least one phosphor in advance. The sheet layer serves as the lighttransmissive layer 28. In FIG. 5E, the sheet member of the phosphorlayer 26 is formed thicker than the sheet member of the lighttransmissive layer 28, however, the thicknesses may be appropriatelyselected. The phosphor layer 26 and the light transmissive layer 28 mayhave the same thickness, or the light transmissive layer 28 may beformed thicker than the phosphor layer 26. Furthermore, a sheet shapedlight transmissive member 25 is used in the above description, but isnot limited thereto. The light transmissive member 25 may be formed byspraying a liquid material, printing, or the like.

Subsequently, as shown in FIG. 4, FIG. 5F, and FIG. 6A, in the step offorming first grooves 32 (S106), the light transmissive members 25 (thephosphor layer 26 and the light transmissive layer 28 stacked thereon)and the first reflective members 18 are partially removed by dicingusing a disk-shaped rotary blade or the like so as to go through thecenter of each first reflective member 18, thereby forming first grooves32 having a prescribed groove width. Here, preferably, the depth of thefirst grooves 32 is defined such that the tips of the first grooves 32are located in the first reflective members 18 after penetrating throughthe light transmissive member 25. In the step of disposing a secondreflective member 20 in the first grooves 32 (S108) as the subsequentstep, all of the lateral faces of the light transmissive member 25 canbe covered with the second reflective member 20. This can alleviatelight leakage from the lateral faces of the light transmissive member 25when the devices are separated in the step of separating into individualpieces (S109).

The first grooves 32 are formed by using a machining apparatus whichemploys a blade that rotates while moving along the center of the firstreflective members 18. In forming the first grooves 32, the machiningoperation may be performed by moving the table on which the substrate 22is placed in the X direction and the Y direction (perpendicular to the Xdirection) while securing the machining apparatus in position, or bymoving the machining apparatus while securing the table in position.Moreover, here, the step of forming second grooves (S107) is performedalong rows which are perpendicular to the first grooves 32. The secondgrooves 34 are formed between rows of a plurality of light emittingelements 16 that are two-dimensionally arranged. The second grooves 34are preferably formed to reach the substrate 22 penetrating through thelight transmissive member 25 and the light guide member 24. In thismanner, in the the step of disposing a second reflective member (S108)as the subsequent step, the lateral faces of light guide members 24located between the rows can be entirely covered with the secondreflective member 20, thereby alleviating escape of the light from thelight guide members 24.

Then, as shown in FIG. 4, FIG. 5G, and FIG. 6B, in the step of disposinga second reflective member S108, the first grooves 32 and the secondgrooves 34 are filled with the second reflective member 20 by transfermolding, injection molding, compression molding, potting, or the like.The second reflective member 20 is formed with the same material as thatof the first reflective members 18 as an example. Here, a removalprocess is performed after curing the second reflective member 20 toadjust the thicknesses of the sheet member of the light transmissivelayer 28 and the second reflective member 20. Here, the removal processis performed so that the light transmissive layer 28 becomes flat andhas a predetermined thickness.

As shown in FIG. 4, FIG. 5H, and FIG. 6C, in the step of separating intoindividual pieces (S109), cuts 38 reaching the adhesive tape 30 are madein the center of the second reflective member 20 along rows and columnsby dicing, using a machining apparatus having a disk-shaped rotaryblade, an ultrasonic cutter having a cutting blade, or a push typecutter. In the step of separating into individual pieces (S109), themachining operation is performed by using a blade having a smallerthickness than one used in forming the first grooves 32 and the secondgrooves 34. The individual light emitting devices 10 remain adhered tothe adhesive sheet 30 after cutting into pieces. Thereafter, removal ofthe adhesive sheet 30 produces individual freestanding light emittingdevices 10.

In the light emitting device 10, the first reflective members 18 areconstructed so that their lower faces are flush with the lower face ofthe substrate 22. Accordingly, the light emitting devices 10 having sucha construction are separated into individual pieces by dicing thereflective member 17 by using a disk-shaped rotary blade, cutting bladeof an ultrasonic cutter, a push-type cutter, or the like, withoutrequirement of cutting the substrate 22. This can simplify theseparation process.

Second Embodiment

Subsequently, a second embodiment of the light emitting device will beexplained primarily with reference to FIG. 7 and FIG. 8. The samereference numerals denote the same parts as those in the firstembodiment for which the explanations are omitted when appropriate.

As shown in FIG. 7, the light emitting device 10A includes thirdreflective members 36 disposed on the substrate 22 to oppose the longsides and/or short sides of the light emitting element 16 in the regionsbetween the first reflective members 18 and the light emitting element16. The third reflective members 36 have opposing oblique or curvedinner faces which are in contact with the inner lateral faces of thefirst reflective members 18, and slanted so that its thickness in adirection from the substrate side towards the light transmissive memberincrease in a direction from the light emitting element side toward thefirst reflective member side. In other words, each of the thirdreflective members 36 has an oblique or curved inner lateral face whichis in contact with an inner lateral face of a first reflective member18, and slanted so that the distance from the lateral surfaces of thelight emitting element 16 to the opposing inner faces of the thirdreflective member 36 gradually increases towards the irradiationdirection Br.

The third reflective members 36 are disposed so as to be lower than theheight of the light emitting element 16. The third reflective members 36are disposed away from the light emitting element 16. The thirdreflective members 36 may be formed with a material that is the same asor different from the material of the first reflective members 18 andthe second reflective member 20. Disposing the third reflective members36 is less likely to cause light absorption by the upper face of thesubstrate 22 while properly guiding light to the emission face 12,thereby further improving the light extraction efficiency.

The light emitting device 10A is manufactured by performing the step ofdisposing the third reflective members before performing the step ofdisposing light guide members (S103) after performing the step ofdisposing the first reflective members (S102) among the steps shown inFIG. 4. That is, as shown in FIG. 8, in the step of disposing the thirdreflective members, the third reflective members 36 are disposed on theinner side of the first reflective members 18 along the directions ofcolumns. The third reflective members 36 whose viscosity is adjusted inadvance are formed to have oblique or curved faces with respect to theemission face 12. After performing the step of disposing the thirdreflective members 36, the step of disposing the light guide member(S103) is performed, followed by the remaining steps as shown in FIG. 4.

Subsequently, third to sixth embodiments will be explained withreference to FIG. 9 to FIG. 12. The same parts as those that havealready been explained will be denoted by the same reference numeralsfor which the explanations will be omitted when appropriate.

Third Embodiment

As shown in FIG. 9, in the light emitting device 10B, the lower faces ofthe first reflective members and the lower face of the substrate 22 areformed to be flush with each other. In detail, the lower ends of thewiring members 14 constructing the lower face of the substrate 22 areformed to be flush with the lower faces of the first reflecting members18. It is also preferable to form the lower face of the substrate 22 tobe flush with the lower faces of the first reflective members 18 in theother embodiments as well. This can realize mounting of the lightemitting device in a stable manner, less likely to be tilted, therebyenhancing the mounting accuracy.

The two wiring members 14 on the lower face side of the substrate 22 mayhave different lengths. Indicating the polarity by giving differentlengths to the wiring members 14 can prevent or alleviate errors inconnecting the light emitting device 10B to an external device.

Fourth Embodiment

As shown in FIG. 10, in the light emitting device 10C, the wiringmembers 14 may be constructed as one that utilizes vias 114 produced byforming through holes in the substrate 22. Vias 114 each include acylindrical inner wall wiring member 114 a disposed on the innercircumferential surface of a through hole formed in the direction ofthickness (i.e., length from the upper surface to the loser surface) ofthe substrate 22, and a filling member 114 b filled in the inner wallwiring member 114 a. For the inner wall wiring member 114 a of a via114, a similar material to that used for the wiring members 14 can beused. The inner wall wiring members 114 a conduct electricity to theelectrodes 15 via the wiring members 14 on the upper face of thesubstrate 22, and are connected to the wiring members 14 formed on thelower face of the substrate 22. The filling members 114 b of vias 114are formed by filling an insulating material, such as an epoxy resin.The filling members 114 b are formed to have a longer length than thethickness of the substrate 22. The wiring members 14 include base wiringmembers 14 a and connection wiring members 14 b. The base wiring members14 a are disposed on the upper face and the lower face of the substrate22 in predetermined areas to surround the upper and lower ends of thefilling member 114 b for electrical conduction with the inner wallwiring members 114 a. The connection wiring members 14 b face the basewiring members 14 a and cover the filling members 114 b to conductelectricity to the electrodes 15. The wiring members 14 are disposed onthe upper face side and the lower face side of the substrateindependently from one another for the electrodes 15, and electricalconduction between the opposing upper and lower wiring members 14 isaccomplished by the inner wall wiring members 114 a.

In the light emitting device 10C, the lower faces of the firstreflective members 18 are disposed to be in contact with the upper faceof the substrate 22. Furthermore, the first reflective members 18 areformed so that their upper faces are positioned higher than the upperface of the light emitting element 16. In the light emitting device 10C,moreover, the second reflective member 20 is formed from around thecenter of the substrate 22 in the thickness direction to the upper faceof the light transmissive member 25.

Fifth Embodiment

As shown in FIG. 11, in the light emitting device 10D, the secondreflective member 20D is formed to have opposing oblique faces 20 d sothat the distance therebetween becomes smaller towards the lighttransmissive member 25D. The second reflective member 20D is formed, forexample, to have a triangular section in the area from the middle of thefirst reflective members 18D in the direction of height to the upperface of the light transmissive member 25D. The formation of the secondreflective member 20D provides the first reflective members 18D withoblique faces at the interfaces with the second reflective member 20D.Furthermore, the formation of the second reflective member 20D providesthe phosphor layer 26D and the light transmissive layer 28D withtrapezoidal sectional shapes. The second reflective member 20D allowsthe upper part of the light transmissive member 25D to have a prescribedwidth. This can more effectively reduce damage of the light transmissivemember 25D that can be caused by the light emitting device 10D cominginto contact with other parts.

In manufacturing the light emitting device 10D, referring to FIG. 5F,the second reflective member 20D can be formed in such a shape byforming the first grooves 32 to have a V-shaped cross section. Thesection of the second reflective member 20D may be trapezoidal,triangular, or staircase shaped, as long as the thickness is set largenear the light transmissive member 25D and set smaller towards thesubstrate 22.

Sixth Embodiment

As shown in FIG. 12, the light emitting device 10E uses similar to thelight emitting device 10C shown by the fourth embodiment, includes aplurality of light emitting elements 16 (e.g. two light emittingelements as shown in FIG. 12). In the light emitting device 10E, inorder to enable simultaneous on/off operations of the two light emittingelements 16, conduction wiring members 14 c connect the base wiringmembers 14 a of one of the wiring members 14 of each so as to mutuallyconduct electricity. The light emitting devices related to the otherembodiments may also be constructed to include a plurality of lightemitting elements as in the case of the light emitting device 10E.

Furthermore, in the first to fifth embodiments explained above, it ispreferable to provide the second reflective member 20 or 20D with highermechanical strength or hardness as compared to the first reflectivemembers 18 or 18D. That is, the second reflective member 20 or 20D canreadily come into contact with other component outside the lightemitting device, such as a light guide plate. Thus providing higherstrength or hardness can attenuate damage such as deformation orchipping even when subjected to an excessive load. Here, in the case ofincreasing the hardness of a member, even if the same base material isused for the first reflective members and the second reflective member,the hardness can be increased, for example, by varying the amount of thesubstance, such as titanium oxide or the like, contained in the member.Moreover, even when the same silicone resin is used, one havingdifferent hardness can be selected, such as using a higher hardnesssilicone resin for the second reflective member 20 or 20D. Furthermore,the second reflective member 20 or 20D and the first reflective members18 or 18D can have different hardness by employing different resinstherebetween. For example, a silicone resin is used for the firstreflective members 18 or 18D, and an epoxy resin which generally hashigher hardness than silicone resins is used for the second reflectivemember 20 or 20D.

The term “higher strength of a member”, means that in the case where thebase material is the same silicone resin, for example, the one havinghigher tensile strength in comparison of the tensile strength. The term“higher strength of a member”, means that in the case where the base isthe same epoxy resin, for example, the one having higher bendingstrength in comparison of the bending strength. In the case of usingdifferent types of resins, for example, one is a silicone resin and theother is an epoxy resin, the magnitude of the strength can be determinedby converting the bending strength or the tensile strength to the otherto be compared.

The hardness or strength of a member can be determined by measuring itusing a known measuring method, such as JIS or the like. The strength ofa member refers to the resistance of the member to deformation ordestruction.

Variations

In each of the embodiments above, it has been explained that throughholes 22 a created in the substrate 22, and the lower faces of the firstreflective members 18 are flush with the lower face of the substrate 22.However, as shown in FIG. 13A, the lower face of the first reflectivemember 18 may be formed partially flush with the lower face of thesubstrate 22. Here, the right and left end portions of the firstreflective member 18 are in contact with the upper face of the substrate22 while the end portion in the center in the longitudinal direction isflush with the lower face of the substrate 22. The lower face of thefirst reflective member 18 serves as both the inside and the outside ofa through hole 22 a as described above, thereby increasing the bondingarea between the substrate 22 and the first reflective member 18,resulting in improvement of adhesion.

Moreover, as shown in FIG. 13B, the first reflective member 18 may bedisposed on the upper face of the substrate 22 without forming a throughhole 22 a in the substrate 22. By disposing the first reflective member18 on the upper face of the substrate 22 in this manner, the amount ofmaterial used for the first reflective member 18 can be reduced ascompared to the case where a through hole 22 a is formed in thesubstrate 22.

Furthermore, the first reflective member 18 and the second reflectivemember 20 may be formed with different materials. The first reflectivemember 18, the second reflective member 20, and the third reflectivemember 36 may be formed with different reflective materials. Changingthe reflective materials can facilitate the adjustment, for example, ofthe light extraction efficiency.

Furthermore, the light transmissive member 25 has been explained asincluding a phosphor layer 26 and a light transmissive layer 28, but itmay be constructed with a light transmissive layer 28 alone, or aphosphor layer 26 alone.

The wavelength conversion substance (e.g., phosphor) used in thephosphor layer 26 can be those described above or those known in theart. Furthermore, the phosphor layer 26 may be disposed as a singlelayer or multiple layers. In the case of constructing the phosphor layeras multiple layers, the wavelength conversion substance may be changedper phosphor layer.

The first reflective members 18 may be disposed to surround the lightemitting element. The first reflective members 18 may be away from alllateral faces of the light emitting element 16. This first reflectivemember 18 has opposing oblique or curved portions in the inner lateralfaces which are slanted so that the distance therebetween increasestowards the light transmissive member 25 from the side close to thesubstrate. In this way, the first reflective member 18 furtherfacilitates extraction of the light emitted by the light emittingelement 16 from the emission face, thereby improving the lightextraction efficiency.

In this case, a substrate is prepared by also creating through holesalong rows as in the case of the through holes 22 a formed alongcolumns.

In the method of manufacturing the light emitting device, the step ofdisposing light transmissive member S105 may be performed withoutperforming the step of partially removing the first reflective members18 and the light guide members 24 (S104). In the case of not performingthe removal step (S104), it is preferable to dispose the light guidemember 24 to the height of the upper ends of the first reflectivemembers 18.

Furthermore, the step of forming the second grooves (S107) may beskipped while performing the operations through the step of separatinginto individual pieces (S109) only with the first grooves. In this case,reflectors capable of reflecting the light from the light emittingelement 16 may be subsequently disposed on the front and rear lateralfaces corresponding to the portions for the second grooves 34.

What is claimed is:
 1. A method of manufacturing a light emitting devicecomprising: arranging a plurality of light emitting elements on asubstrate, disposing first reflective members so as to positionedbetween or surrounding the light emitting elements while being away fromthe light emitting elements, disposing a light guide member covering thelight emitting elements and in contact with the first reflectivemembers, disposing a light transmissive member on the light guide memberand the first light reflective members, forming first grooves bypartially removing the light transmissive member and the firstreflective members, disposing a second reflective member in the firstgrooves so as to be in contact with the light transmissive member andthe first reflective members, and separating into individual pieces bycutting the second reflective member.
 2. The method of manufacturing alight emitting device according to claim 1, wherein the light emittingelements are arranged in rows and columns, and the step of disposingfirst reflective members is disposing the first reflective members onlyon intervals between the light emitting elements in columns.
 3. Themethod of manufacturing a light emitting device according to claim 2,further comprising forming second grooves by partially removing thelight guide member and the light transmissive member on intervalsbetween the light emitting elements arranged in rows before the step ofdisposing a second reflective member, wherein the step of disposing asecond reflective member includes disposing the second reflective memberin the second grooves so as to be in contact with the light transmissivemember and the light guide member.
 4. The method of manufacturing alight emitting device according to claim 1, wherein the step ofdisposing a light transmissive member is disposing a light transmissivemember so as to cover upper faces of the light guide member and thefirst reflective members, and the step of disposing a light transmissivemember further includes partially removing the first reflective membersand the light guide member while retaining the light guide memberpositioned in an upper surface side of the light emitting elements,before the step of disposing a light transmissive member.
 5. The methodof manufacturing a light emitting device according to claim 1, whereinthe substrate has at least one through hole, and the method furtherincludes forming portions of the first reflective members in the atleast one through hole.
 6. The method of manufacturing a light emittingdevice according to claim 1 further comprising, before the step ofdisposing a light guide member, disposing one or more third reflectivemembers on the substrate so as to have oblique or curved inner facesthat are in contact with the inner lateral faces of the first reflectivemembers and slanted so that a thickness in a direction from thesubstrate side towards the light transmissive member increases in adirection from the light emitting element side toward the firstreflective member side.